Prevalence of Anti-Heparin Platelet Factor 4 Antibodies in Patients with Disseminated Intravascular Coagulation.

Abstract 2094

Poster Board II-71

Disseminated intravascular coagulation (DIC) represents a complex syndrome with multiple pathophysiologic components. Most patients with DIC exhibit thrombocytopenic responses due to endogenous consumption of platelets. A systematic study on the prevalence on anti-heparin platelet factor 4 (AHPF4) antibodies and HIT syndrome in DIC patients has not been presented. To determine the prevalence of AHPF4 antibodies in patients with suspected DIC syndrome a total of 25 plasma samples were retrospectively analyzed utilizing the two commercially available methods (GTI, Brookfield, WI and Hyphen Biomedical, Paris, France). Out of 25 patients, 24 samples were positive for the AHPF4 antibody in the GTI method (OD>0.400), whereas only 16 were positive in the Hyphen Biomedical assay (OD>0.500). Interestingly, only 9 samples were positive in both of these assays. None of the positive samples in either the GTI or the Hyphen assay exhibited a positive ¹⁴C serotonin response. Additional analysis of these samples revealed that only 8 of these patients were previously exposed to heparin. Only 4 of the baseline samples were found to contain low levels of heparin as measured by anti-Xa method (< 0.2 U/ml). Additional analysis of these samples revealed the presence of platelet activation products such as platelet factor 4 (PF4), selectin and p-selectin. These studies suggest that circulating AHPF4 antibodies are non-functional and do not produce any thrombocytopenic responses. The elevated circulating PF4 levels and other cytokines may be contributory to the generation of these antibodies in the DIC patients.